arachnodactyly
n. [医] 细长指;[医] 蜘蛛脚样指
例句
Both persons were of the same height, 188 cm. However, note that the hand at the left demonstrates arachnodactyly.
两人身高均为188厘米,注意不同的是,左边的手有蜘蛛样指。